/**
 * @file
 * Sockets BSD-Like API module
 *
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 *modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 *EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 *PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 * Improved by Marc Boucher <marc@mbsi.ca> and David Haas <dhaas@alum.rpi.edu>
 *
 */

#include "lwip/opt.h"

#if LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */

#include "lwip/sockets.h"
#include "lwip/api.h"
#include "lwip/sys.h"
#include "lwip/igmp.h"
#include "lwip/inet.h"
#include "lwip/tcp.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/tcpip.h"
#include "lwip/pbuf.h"
#if LWIP_CHECKSUM_ON_COPY
#include "lwip/inet_chksum.h"
#endif

#include <string.h>

#define NUM_SOCKETS MEMP_NUM_NETCONN

/** Contains all internal pointers and states used for a socket */
struct lwip_sock {
  /** sockets currently are built on netconns, each socket has one netconn */
  struct netconn *conn;
  /** data that was left from the previous read */
  void *lastdata;
  /** offset in the data that was left from the previous read */
  u16_t lastoffset;
  /** number of times data was received, set by event_callback(),
      tested by the receive and select functions */
  s16_t rcvevent;
  /** number of times data was ACKed (free send buffer), set by
     event_callback(),
      tested by select */
  u16_t sendevent;
  /** error happened for this socket, set by event_callback(), tested by select
   */
  u16_t errevent;
  /** last error that occurred on this socket */
  int err;
  /** counter of how many threads are waiting for this socket using select */
  int select_waiting;
};

/** Description for a task waiting in select */
struct lwip_select_cb {
  /** Pointer to the next waiting task */
  struct lwip_select_cb *next;
  /** Pointer to the previous waiting task */
  struct lwip_select_cb *prev;
  /** readset passed to select */
  fd_set *readset;
  /** writeset passed to select */
  fd_set *writeset;
  /** unimplemented: exceptset passed to select */
  fd_set *exceptset;
  /** don't signal the same semaphore twice: set to 1 when signalled */
  int sem_signalled;
  /** semaphore to wake up a task waiting for select */
  sys_sem_t sem;
};

/** This struct is used to pass data to the set/getsockopt_internal
 * functions running in tcpip_thread context (only a void* is allowed) */
struct lwip_setgetsockopt_data {
  /** socket struct for which to change options */
  struct lwip_sock *sock;
#ifdef LWIP_DEBUG
  /** socket index for which to change options */
  int s;
#endif /* LWIP_DEBUG */
  /** level of the option to process */
  int level;
  /** name of the option to process */
  int optname;
  /** set: value to set the option to
    * get: value of the option is stored here */
  void *optval;
  /** size of *optval */
  socklen_t *optlen;
  /** if an error occures, it is temporarily stored here */
  err_t err;
};

/** The global array of available sockets */
static struct lwip_sock sockets[NUM_SOCKETS];
/** The global list of tasks waiting for select */
static struct lwip_select_cb *select_cb_list;
/** This counter is increased from lwip_select when the list is chagned
    and checked in event_callback to see if it has changed. */
static volatile int select_cb_ctr;

/** Table to quickly map an lwIP error (err_t) to a socket error
  * by using -err as an index */
static const int err_to_errno_table[] = {
    0,            /* ERR_OK          0      No error, everything OK. */
    ENOMEM,       /* ERR_MEM        -1      Out of memory error.     */
    ENOBUFS,      /* ERR_BUF        -2      Buffer error.            */
    EWOULDBLOCK,  /* ERR_TIMEOUT    -3      Timeout                  */
    EHOSTUNREACH, /* ERR_RTE        -4      Routing problem.         */
    EINPROGRESS,  /* ERR_INPROGRESS -5      Operation in progress    */
    EINVAL,       /* ERR_VAL        -6      Illegal value.           */
    EWOULDBLOCK,  /* ERR_WOULDBLOCK -7      Operation would block.   */
    /*++ Changed by Espressif ++*/
    ECONNABORTED, /* ERR_ABRT       -8      Connection aborted.      */
    ECONNRESET,   /* ERR_RST        -9      Connection reset.        */
    ESHUTDOWN,    /* ERR_CLSD       -10     Connection closed.       */
    ENOTCONN,     /* ERR_CONN       -11     Not connected.           */
    EIO,          /* ERR_ARG        -12     Illegal argument.        */
    EADDRINUSE,   /* ERR_USE        -13     Address in use.          */
    -1,           /* ERR_IF         -14     Low-level netif error    */
    -1,           /* ERR_ISCONN     -15     Already connected.       */
                  /*--                      --*/
};

#define ERR_TO_ERRNO_TABLE_SIZE \
  (sizeof(err_to_errno_table) / sizeof(err_to_errno_table[0]))

#define err_to_errno(err)                                                     \
  ((unsigned) (-(err)) < ERR_TO_ERRNO_TABLE_SIZE ? err_to_errno_table[-(err)] \
                                                 : EIO)

#ifdef ERRNO
#ifndef set_errno
#define set_errno(err) errno = (err)
#endif
#else /* ERRNO */
#define set_errno(err)
#endif /* ERRNO */

#define sock_set_errno(sk, e) \
  do {                        \
    sk->err = (e);            \
    set_errno(sk->err);       \
  } while (0)

/* Forward delcaration of some functions */
static void event_callback(struct netconn *conn, enum netconn_evt evt,
                           u16_t len);
static void lwip_getsockopt_internal(void *arg);
static void lwip_setsockopt_internal(void *arg);

/**
 * Initialize this module. This function has to be called before any other
 * functions in this module!
 */
void lwip_socket_init(void) {
}

/**
 * Map a externally used socket index to the internal socket representation.
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
static struct lwip_sock *get_socket(int s) {
  struct lwip_sock *sock;

  if ((s < 0) || (s >= NUM_SOCKETS)) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): invalid\n", s));
    set_errno(EBADF);
    return NULL;
  }

  sock = &sockets[s];

  if (!sock->conn) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): not active\n", s));
    set_errno(EBADF);
    return NULL;
  }

  return sock;
}

/**
 * Same as get_socket but doesn't set errno
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
static struct lwip_sock *tryget_socket(int s) {
  if ((s < 0) || (s >= NUM_SOCKETS)) {
    return NULL;
  }
  if (!sockets[s].conn) {
    return NULL;
  }
  return &sockets[s];
}

/**
 * Allocate a new socket for a given netconn.
 *
 * @param newconn the netconn for which to allocate a socket
 * @param accepted 1 if socket has been created by accept(),
 *                 0 if socket has been created by socket()
 * @return the index of the new socket; -1 on error
 */
static int alloc_socket(struct netconn *newconn, int accepted) {
  int i;
  SYS_ARCH_DECL_PROTECT(lev);

  /* allocate a new socket identifier */
  for (i = 0; i < NUM_SOCKETS; ++i) {
    /* Protect socket array */
    SYS_ARCH_PROTECT(lev);
    if (!sockets[i].conn) {
      sockets[i].conn = newconn;
      /* The socket is not yet known to anyone, so no need to protect
         after having marked it as used. */
      SYS_ARCH_UNPROTECT(lev);
      sockets[i].lastdata = NULL;
      sockets[i].lastoffset = 0;
      sockets[i].rcvevent = 0;
      /* TCP sendbuf is empty, but the socket is not yet writable until
       * connected
       * (unless it has been created by accept()). */
      sockets[i].sendevent =
          (newconn->type == NETCONN_TCP ? (accepted != 0) : 1);
      sockets[i].errevent = 0;
      sockets[i].err = 0;
      sockets[i].select_waiting = 0;
      return i;
    }
    SYS_ARCH_UNPROTECT(lev);
  }
  return -1;
}

/** Free a socket. The socket's netconn must have been
 * delete before!
 *
 * @param sock the socket to free
 * @param is_tcp != 0 for TCP sockets, used to free lastdata
 */
static void free_socket(struct lwip_sock *sock, int is_tcp) {
  void *lastdata;
  SYS_ARCH_DECL_PROTECT(lev);

  lastdata = sock->lastdata;
  sock->lastdata = NULL;
  sock->lastoffset = 0;
  sock->err = 0;

  /* Protect socket array */
  SYS_ARCH_PROTECT(lev);
  sock->conn = NULL;
  SYS_ARCH_UNPROTECT(lev);
  /* don't use 'sock' after this line, as another task might have allocated it
   */

  if (lastdata != NULL) {
    if (is_tcp) {
      pbuf_free((struct pbuf *) lastdata);
    } else {
      netbuf_delete((struct netbuf *) lastdata);
    }
  }
}

/* Below this, the well-known socket functions are implemented.
 * Use google.com or opengroup.org to get a good description :-)
 *
 * Exceptions are documented!
 */

int lwip_accept(int s, struct sockaddr *addr, socklen_t *addrlen) {
  struct lwip_sock *sock, *nsock;
  struct netconn *newconn;
  ip_addr_t naddr;
  u16_t port;
  int newsock;
  struct sockaddr_in sin;
  err_t err;
  SYS_ARCH_DECL_PROTECT(lev);

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d)...\n", s));
  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  if (netconn_is_nonblocking(sock->conn) && (sock->rcvevent <= 0)) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): returning EWOULDBLOCK\n", s));
    sock_set_errno(sock, EWOULDBLOCK);
    return -1;
  }

  /* wait for a new connection */
  err = netconn_accept(sock->conn, &newconn);
  if (err != ERR_OK) {
    LWIP_DEBUGF(SOCKETS_DEBUG,
                ("lwip_accept(%d): netconn_acept failed, err=%d\n", s, err));
    if (netconn_type(sock->conn) != NETCONN_TCP) {
      sock_set_errno(sock, EOPNOTSUPP);
      return EOPNOTSUPP;
    }
    sock_set_errno(sock, err_to_errno(err));
    return -1;
  }
  LWIP_ASSERT("newconn != NULL", newconn != NULL);
  /* Prevent automatic window updates, we do this on our own! */
  netconn_set_noautorecved(newconn, 1);

  /* get the IP address and port of the remote host */
  err = netconn_peer(newconn, &naddr, &port);
  if (err != ERR_OK) {
    LWIP_DEBUGF(SOCKETS_DEBUG,
                ("lwip_accept(%d): netconn_peer failed, err=%d\n", s, err));
    netconn_delete(newconn);
    sock_set_errno(sock, err_to_errno(err));
    return -1;
  }

  /* Note that POSIX only requires us to check addr is non-NULL. addrlen must
   * not be NULL if addr is valid.
   */
  if (NULL != addr) {
    LWIP_ASSERT("addr valid but addrlen NULL", addrlen != NULL);
    memset(&sin, 0, sizeof(sin));
    sin.sin_len = sizeof(sin);
    sin.sin_family = AF_INET;
    sin.sin_port = htons(port);
    inet_addr_from_ipaddr(&sin.sin_addr, &naddr);

    if (*addrlen > sizeof(sin)) *addrlen = sizeof(sin);

    MEMCPY(addr, &sin, *addrlen);
  }

  newsock = alloc_socket(newconn, 1);
  if (newsock == -1) {
    netconn_delete(newconn);
    sock_set_errno(sock, ENFILE);
    return -1;
  }
  LWIP_ASSERT("invalid socket index",
              (newsock >= 0) && (newsock < NUM_SOCKETS));
  LWIP_ASSERT("newconn->callback == event_callback",
              newconn->callback == event_callback);
  nsock = &sockets[newsock];

  /* See event_callback: If data comes in right away after an accept, even
   * though the server task might not have created a new socket yet.
   * In that case, newconn->socket is counted down (newconn->socket--),
   * so nsock->rcvevent is >= 1 here!
   */
  SYS_ARCH_PROTECT(lev);
  nsock->rcvevent += (s16_t)(-1 - newconn->socket);
  newconn->socket = newsock;
  SYS_ARCH_UNPROTECT(lev);

  LWIP_DEBUGF(SOCKETS_DEBUG,
              ("lwip_accept(%d) returning new sock=%d addr=", s, newsock));
  ip_addr_debug_print(SOCKETS_DEBUG, &naddr);
  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F "\n", port));

  sock_set_errno(sock, 0);
  return newsock;
}

int lwip_bind(int s, const struct sockaddr *name, socklen_t namelen) {
  struct lwip_sock *sock;
  ip_addr_t local_addr;
  u16_t local_port;
  err_t err;
  const struct sockaddr_in *name_in;

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  /* check size, familiy and alignment of 'name' */
  LWIP_ERROR(
      "lwip_bind: invalid address",
      ((namelen == sizeof(struct sockaddr_in)) &&
       ((name->sa_family) == AF_INET) && ((((mem_ptr_t) name) % 4) == 0)),
      sock_set_errno(sock, err_to_errno(ERR_ARG));
      return -1;);
  name_in = (const struct sockaddr_in *) (void *) name;

  inet_addr_to_ipaddr(&local_addr, &name_in->sin_addr);
  local_port = name_in->sin_port;

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d, addr=", s));
  ip_addr_debug_print(SOCKETS_DEBUG, &local_addr);
  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F ")\n", ntohs(local_port)));

  err = netconn_bind(sock->conn, &local_addr, ntohs(local_port));

  if (err != ERR_OK) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) failed, err=%d\n", s, err));
    sock_set_errno(sock, err_to_errno(err));
    return -1;
  }

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) succeeded\n", s));
  sock_set_errno(sock, 0);
  return 0;
}

int lwip_close(int s) {
  struct lwip_sock *sock;
  int is_tcp = 0;

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_close(%d)\n", s));

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  if (sock->conn != NULL) {
    is_tcp = netconn_type(sock->conn) == NETCONN_TCP;
  } else {
    LWIP_ASSERT("sock->lastdata == NULL", sock->lastdata == NULL);
  }

  netconn_delete(sock->conn);

  free_socket(sock, is_tcp);
  set_errno(0);
  return 0;
}

int lwip_connect(int s, const struct sockaddr *name, socklen_t namelen) {
  struct lwip_sock *sock;
  err_t err;
  const struct sockaddr_in *name_in;

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  /* check size, familiy and alignment of 'name' */
  LWIP_ERROR(
      "lwip_connect: invalid address",
      ((namelen == sizeof(struct sockaddr_in)) &&
       ((name->sa_family) == AF_INET) && ((((mem_ptr_t) name) % 4) == 0)),
      sock_set_errno(sock, err_to_errno(ERR_ARG));
      return -1;);
  name_in = (const struct sockaddr_in *) (void *) name;

  if (name_in->sin_family == AF_UNSPEC) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
    err = netconn_disconnect(sock->conn);
  } else {
    ip_addr_t remote_addr;
    u16_t remote_port;

    inet_addr_to_ipaddr(&remote_addr, &name_in->sin_addr);
    remote_port = name_in->sin_port;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, addr=", s));
    ip_addr_debug_print(SOCKETS_DEBUG, &remote_addr);
    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F ")\n", ntohs(remote_port)));

    err = netconn_connect(sock->conn, &remote_addr, ntohs(remote_port));
  }

  if (err != ERR_OK) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) failed, err=%d\n", s, err));
    sock_set_errno(sock, err_to_errno(err));
    return -1;
  }

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) succeeded\n", s));
  sock_set_errno(sock, 0);
  return 0;
}

/**
 * Set a socket into listen mode.
 * The socket may not have been used for another connection previously.
 *
 * @param s the socket to set to listening mode
 * @param backlog (ATTENTION: needs TCP_LISTEN_BACKLOG=1)
 * @return 0 on success, non-zero on failure
 */
int lwip_listen(int s, int backlog) {
  struct lwip_sock *sock;
  err_t err;

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d, backlog=%d)\n", s, backlog));

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  /* limit the "backlog" parameter to fit in an u8_t */
  backlog = LWIP_MIN(LWIP_MAX(backlog, 0), 0xff);

  err = netconn_listen_with_backlog(sock->conn, (u8_t) backlog);

  if (err != ERR_OK) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d) failed, err=%d\n", s, err));
    if (netconn_type(sock->conn) != NETCONN_TCP) {
      sock_set_errno(sock, EOPNOTSUPP);
      return EOPNOTSUPP;
    }
    sock_set_errno(sock, err_to_errno(err));
    return -1;
  }

  sock_set_errno(sock, 0);
  return 0;
}

int lwip_recvfrom(int s, void *mem, size_t len, int flags,
                  struct sockaddr *from, socklen_t *fromlen) {
  struct lwip_sock *sock;
  void *buf = NULL;
  struct pbuf *p;
  u16_t buflen, copylen;
  int off = 0;
  ip_addr_t *addr;
  u16_t port;
  u8_t done = 0;
  err_t err;

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d, %p, %" SZT_F ", 0x%x, ..)\n",
                              s, mem, len, flags));
  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  do {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: top while sock->lastdata=%p\n",
                                sock->lastdata));
    /* Check if there is data left from the last recv operation. */
    if (sock->lastdata) {
      buf = sock->lastdata;
    } else {
      /* If this is non-blocking call, then check first */
      if (((flags & MSG_DONTWAIT) || netconn_is_nonblocking(sock->conn)) &&
          (sock->rcvevent <= 0)) {
        if (off > 0) {
          /* update receive window */
          netconn_recved(sock->conn, (u32_t) off);
          /* already received data, return that */
          sock_set_errno(sock, 0);
          return off;
        }
        LWIP_DEBUGF(SOCKETS_DEBUG,
                    ("lwip_recvfrom(%d): returning EWOULDBLOCK\n", s));
        sock_set_errno(sock, EWOULDBLOCK);
        return -1;
      }

      /* No data was left from the previous operation, so we try to get
         some from the network. */
      if (netconn_type(sock->conn) == NETCONN_TCP) {
        err = netconn_recv_tcp_pbuf(sock->conn, (struct pbuf **) &buf);
      } else {
        err = netconn_recv(sock->conn, (struct netbuf **) &buf);
      }
      LWIP_DEBUGF(
          SOCKETS_DEBUG,
          ("lwip_recvfrom: netconn_recv err=%d, netbuf=%p\n", err, buf));

      if (err != ERR_OK) {
        if (off > 0) {
          /* update receive window */
          netconn_recved(sock->conn, (u32_t) off);
          /* already received data, return that */
          sock_set_errno(sock, 0);
          return off;
        }
        /* We should really do some error checking here. */
        LWIP_DEBUGF(SOCKETS_DEBUG,
                    ("lwip_recvfrom(%d): buf == NULL, error is \"%s\"!\n", s,
                     lwip_strerr(err)));
        sock_set_errno(sock, err_to_errno(err));
        if (err == ERR_CLSD) {
          return 0;
        } else {
          return -1;
        }
      }
      LWIP_ASSERT("buf != NULL", buf != NULL);
      sock->lastdata = buf;
    }

    if (netconn_type(sock->conn) == NETCONN_TCP) {
      p = (struct pbuf *) buf;
    } else {
      p = ((struct netbuf *) buf)->p;
    }
    buflen = p->tot_len;
    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: buflen=%" U16_F " len=%" SZT_F
                                " off=%d sock->lastoffset=%" U16_F "\n",
                                buflen, len, off, sock->lastoffset));

    buflen -= sock->lastoffset;

    if (len > buflen) {
      copylen = buflen;
    } else {
      copylen = (u16_t) len;
    }

    /* copy the contents of the received buffer into
    the supplied memory pointer mem */
    pbuf_copy_partial(p, (u8_t *) mem + off, copylen, sock->lastoffset);

    off += copylen;

    if (netconn_type(sock->conn) == NETCONN_TCP) {
      LWIP_ASSERT("invalid copylen, len would underflow", len >= copylen);
      len -= copylen;
      if ((len <= 0) || (p->flags & PBUF_FLAG_PUSH) || (sock->rcvevent <= 0) ||
          ((flags & MSG_PEEK) != 0)) {
        done = 1;
      }
    } else {
      done = 1;
    }

    /* Check to see from where the data was.*/
    if (done) {
      ip_addr_t fromaddr;
      if (from && fromlen) {
        struct sockaddr_in sin;

        if (netconn_type(sock->conn) == NETCONN_TCP) {
          addr = &fromaddr;
          netconn_getaddr(sock->conn, addr, &port, 0);
        } else {
          addr = netbuf_fromaddr((struct netbuf *) buf);
          port = netbuf_fromport((struct netbuf *) buf);
        }

        memset(&sin, 0, sizeof(sin));
        sin.sin_len = sizeof(sin);
        sin.sin_family = AF_INET;
        sin.sin_port = htons(port);
        inet_addr_from_ipaddr(&sin.sin_addr, addr);

        if (*fromlen > sizeof(sin)) {
          *fromlen = sizeof(sin);
        }

        MEMCPY(from, &sin, *fromlen);

        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): addr=", s));
        ip_addr_debug_print(SOCKETS_DEBUG, addr);
        LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F " len=%d\n", port, off));
      } else {
#if SOCKETS_DEBUG
        if (netconn_type(sock->conn) == NETCONN_TCP) {
          addr = &fromaddr;
          netconn_getaddr(sock->conn, addr, &port, 0);
        } else {
          addr = netbuf_fromaddr((struct netbuf *) buf);
          port = netbuf_fromport((struct netbuf *) buf);
        }

        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): addr=", s));
        ip_addr_debug_print(SOCKETS_DEBUG, addr);
        LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F " len=%d\n", port, off));
#endif /*  SOCKETS_DEBUG */
      }
    }

    /* If we don't peek the incoming message... */
    if ((flags & MSG_PEEK) == 0) {
      /* If this is a TCP socket, check if there is data left in the
         buffer. If so, it should be saved in the sock structure for next
         time around. */
      if ((netconn_type(sock->conn) == NETCONN_TCP) && (buflen - copylen > 0)) {
        sock->lastdata = buf;
        sock->lastoffset += copylen;
        LWIP_DEBUGF(SOCKETS_DEBUG,
                    ("lwip_recvfrom: lastdata now netbuf=%p\n", buf));
      } else {
        sock->lastdata = NULL;
        sock->lastoffset = 0;
        LWIP_DEBUGF(SOCKETS_DEBUG,
                    ("lwip_recvfrom: deleting netbuf=%p\n", buf));
        if (netconn_type(sock->conn) == NETCONN_TCP) {
          pbuf_free((struct pbuf *) buf);
        } else {
          netbuf_delete((struct netbuf *) buf);
        }
      }
    }
  } while (!done);

  if (off > 0) {
    /* update receive window */
    netconn_recved(sock->conn, (u32_t) off);
  }
  sock_set_errno(sock, 0);
  return off;
}

int lwip_read(int s, void *mem, size_t len) {
  return lwip_recvfrom(s, mem, len, 0, NULL, NULL);
}

int lwip_recv(int s, void *mem, size_t len, int flags) {
  return lwip_recvfrom(s, mem, len, flags, NULL, NULL);
}

int lwip_send(int s, const void *data, size_t size, int flags) {
  struct lwip_sock *sock;
  err_t err;
  u8_t write_flags;
  size_t written;

  LWIP_DEBUGF(SOCKETS_DEBUG,
              ("lwip_send(%d, data=%p, size=%" SZT_F ", flags=0x%x)\n", s, data,
               size, flags));

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  if (sock->conn->type != NETCONN_TCP) {
#if (LWIP_UDP || LWIP_RAW)
    return lwip_sendto(s, data, size, flags, NULL, 0);
#else  /* (LWIP_UDP || LWIP_RAW) */
    sock_set_errno(sock, err_to_errno(ERR_ARG));
    return -1;
#endif /* (LWIP_UDP || LWIP_RAW) */
  }

  write_flags = NETCONN_COPY | ((flags & MSG_MORE) ? NETCONN_MORE : 0) |
                ((flags & MSG_DONTWAIT) ? NETCONN_DONTBLOCK : 0);
  written = 0;
  err = netconn_write_partly(sock->conn, data, size, write_flags, &written);

  LWIP_DEBUGF(SOCKETS_DEBUG,
              ("lwip_send(%d) err=%d written=%" SZT_F "\n", s, err, written));
  sock_set_errno(sock, err_to_errno(err));
  return (err == ERR_OK ? (int) written : -1);
}

int lwip_sendto(int s, const void *data, size_t size, int flags,
                const struct sockaddr *to, socklen_t tolen) {
  struct lwip_sock *sock;
  err_t err;
  u16_t short_size;
  const struct sockaddr_in *to_in;
  u16_t remote_port;
#if !LWIP_TCPIP_CORE_LOCKING
  struct netbuf buf;
#endif

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  if (sock->conn->type == NETCONN_TCP) {
#if LWIP_TCP
    return lwip_send(s, data, size, flags);
#else  /* LWIP_TCP */
    LWIP_UNUSED_ARG(flags);
    sock_set_errno(sock, err_to_errno(ERR_ARG));
    return -1;
#endif /* LWIP_TCP */
  }

  /* @todo: split into multiple sendto's? */
  LWIP_ASSERT("lwip_sendto: size must fit in u16_t", size <= 0xffff);
  short_size = (u16_t) size;
  LWIP_ERROR("lwip_sendto: invalid address",
             (((to == NULL) && (tolen == 0)) ||
              ((tolen == sizeof(struct sockaddr_in)) &&
               ((to->sa_family) == AF_INET) && ((((mem_ptr_t) to) % 4) == 0))),
             sock_set_errno(sock, err_to_errno(ERR_ARG));
             return -1;);
  to_in = (const struct sockaddr_in *) (void *) to;

#if LWIP_TCPIP_CORE_LOCKING
  /* Should only be consider like a sample or a simple way to experiment this
   * option (no check of "to" field...) */
  {
    struct pbuf *p;
    ip_addr_t *remote_addr;

#if LWIP_NETIF_TX_SINGLE_PBUF
    p = pbuf_alloc(PBUF_TRANSPORT, short_size, PBUF_RAM);
    if (p != NULL) {
#if LWIP_CHECKSUM_ON_COPY
      u16_t chksum = 0;
      if (sock->conn->type != NETCONN_RAW) {
        chksum = LWIP_CHKSUM_COPY(p->payload, data, short_size);
      } else
#endif /* LWIP_CHECKSUM_ON_COPY */
        MEMCPY(p->payload, data, size);
#else  /* LWIP_NETIF_TX_SINGLE_PBUF */
    p = pbuf_alloc(PBUF_TRANSPORT, short_size, PBUF_REF);
    if (p != NULL) {
      p->payload = (void *) data;
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */

      if (to_in != NULL) {
        inet_addr_to_ipaddr_p(remote_addr, &to_in->sin_addr);
        remote_port = ntohs(to_in->sin_port);
      } else {
        /*++ Changed by Espressif ++*/
        remote_addr = IP_ADDR_ANY;
        remote_port = 0;
        /*--                      --*/
      }

      LOCK_TCPIP_CORE();
      if (netconn_type(sock->conn) == NETCONN_RAW) {
#if LWIP_RAW
        err = sock->conn->last_err =
            raw_sendto(sock->conn->pcb.raw, p, remote_addr);
#else  /* LWIP_RAW */
        err = ERR_ARG;
#endif /* LWIP_RAW */
      }
#if LWIP_UDP && LWIP_RAW
      else
#endif /* LWIP_UDP && LWIP_RAW */
      {
#if LWIP_UDP
#if LWIP_CHECKSUM_ON_COPY && LWIP_NETIF_TX_SINGLE_PBUF
        err = sock->conn->last_err = udp_sendto_chksum(
            sock->conn->pcb.udp, p, remote_addr, remote_port, 1, chksum);
#else  /* LWIP_CHECKSUM_ON_COPY && LWIP_NETIF_TX_SINGLE_PBUF */
        err = sock->conn->last_err =
            udp_sendto(sock->conn->pcb.udp, p, remote_addr, remote_port);
#endif /* LWIP_CHECKSUM_ON_COPY && LWIP_NETIF_TX_SINGLE_PBUF */
#else  /* LWIP_UDP */
        err = ERR_ARG;
#endif /* LWIP_UDP */
      }
      UNLOCK_TCPIP_CORE();

      pbuf_free(p);
    } else {
      err = ERR_MEM;
    }
  }
#else /* LWIP_TCPIP_CORE_LOCKING */
  /* initialize a buffer */
  buf.p = buf.ptr = NULL;
#if LWIP_CHECKSUM_ON_COPY
  buf.flags = 0;
#endif /* LWIP_CHECKSUM_ON_COPY */
  if (to) {
    inet_addr_to_ipaddr(&buf.addr, &to_in->sin_addr);
    remote_port = ntohs(to_in->sin_port);
    netbuf_fromport(&buf) = remote_port;
  } else {
    remote_port = 0;
    ip_addr_set_any(&buf.addr);
    netbuf_fromport(&buf) = 0;
  }

  LWIP_DEBUGF(SOCKETS_DEBUG,
              ("lwip_sendto(%d, data=%p, short_size=%" U16_F ", flags=0x%x to=",
               s, data, short_size, flags));
  ip_addr_debug_print(SOCKETS_DEBUG, &buf.addr);
  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F "\n", remote_port));

/* make the buffer point to the data that should be sent */
#if LWIP_NETIF_TX_SINGLE_PBUF
  /* Allocate a new netbuf and copy the data into it. */
  if (netbuf_alloc(&buf, short_size) == NULL) {
    err = ERR_MEM;
  } else {
#if LWIP_CHECKSUM_ON_COPY
    if (sock->conn->type != NETCONN_RAW) {
      u16_t chksum = LWIP_CHKSUM_COPY(buf.p->payload, data, short_size);
      netbuf_set_chksum(&buf, chksum);
      err = ERR_OK;
    } else
#endif /* LWIP_CHECKSUM_ON_COPY */
    {
      err = netbuf_take(&buf, data, short_size);
    }
  }
#else /* LWIP_NETIF_TX_SINGLE_PBUF */
  err = netbuf_ref(&buf, data, short_size);
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
  if (err == ERR_OK) {
    /* send the data */
    err = netconn_send(sock->conn, &buf);
  }

  /* deallocated the buffer */
  netbuf_free(&buf);
#endif /* LWIP_TCPIP_CORE_LOCKING */
  sock_set_errno(sock, err_to_errno(err));
  return (err == ERR_OK ? short_size : -1);
}

int lwip_socket(int domain, int type, int protocol) {
  struct netconn *conn;
  int i;

  LWIP_UNUSED_ARG(domain);

  /* create a netconn */
  switch (type) {
    case SOCK_RAW:
      conn = netconn_new_with_proto_and_callback(NETCONN_RAW, (u8_t) protocol,
                                                 event_callback);
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_socket(%s, SOCK_RAW, %d) = ",
                   domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
      break;
    case SOCK_DGRAM:
      conn = netconn_new_with_callback(
          (protocol == IPPROTO_UDPLITE) ? NETCONN_UDPLITE : NETCONN_UDP,
          event_callback);
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_socket(%s, SOCK_DGRAM, %d) = ",
                   domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
      break;
    case SOCK_STREAM:
      conn = netconn_new_with_callback(NETCONN_TCP, event_callback);
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_socket(%s, SOCK_STREAM, %d) = ",
                   domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
      if (conn != NULL) {
        /* Prevent automatic window updates, we do this on our own! */
        netconn_set_noautorecved(conn, 1);
      }
      break;
    default:
      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%d, %d/UNKNOWN, %d) = -1\n",
                                  domain, type, protocol));
      set_errno(EINVAL);
      return -1;
  }

  if (!conn) {
    LWIP_DEBUGF(SOCKETS_DEBUG, ("-1 / ENOBUFS (could not create netconn)\n"));
    set_errno(ENOBUFS);
    return -1;
  }

  i = alloc_socket(conn, 0);

  if (i == -1) {
    netconn_delete(conn);
    set_errno(ENFILE);
    return -1;
  }
  conn->socket = i;
  LWIP_DEBUGF(SOCKETS_DEBUG, ("%d\n", i));
  set_errno(0);
  return i;
}

int lwip_write(int s, const void *data, size_t size) {
  return lwip_send(s, data, size, 0);
}

/**
 * Go through the readset and writeset lists and see which socket of the sockets
 * set in the sets has events. On return, readset, writeset and exceptset have
 * the sockets enabled that had events.
 *
 * exceptset is not used for now!!!
 *
 * @param maxfdp1 the highest socket index in the sets
 * @param readset_in:    set of sockets to check for read events
 * @param writeset_in:   set of sockets to check for write events
 * @param exceptset_in:  set of sockets to check for error events
 * @param readset_out:   set of sockets that had read events
 * @param writeset_out:  set of sockets that had write events
 * @param exceptset_out: set os sockets that had error events
 * @return number of sockets that had events (read/write/exception) (>= 0)
 */
static int lwip_selscan(int maxfdp1, fd_set *readset_in, fd_set *writeset_in,
                        fd_set *exceptset_in, fd_set *readset_out,
                        fd_set *writeset_out, fd_set *exceptset_out) {
  int i, nready = 0;
  fd_set lreadset, lwriteset, lexceptset;
  struct lwip_sock *sock;
  SYS_ARCH_DECL_PROTECT(lev);

  FD_ZERO(&lreadset);
  FD_ZERO(&lwriteset);
  FD_ZERO(&lexceptset);

  /* Go through each socket in each list to count number of sockets which
     currently match */
  for (i = 0; i < maxfdp1; i++) {
    void *lastdata = NULL;
    s16_t rcvevent = 0;
    u16_t sendevent = 0;
    u16_t errevent = 0;
    /* First get the socket's status (protected)... */
    SYS_ARCH_PROTECT(lev);
    sock = tryget_socket(i);
    if (sock != NULL) {
      lastdata = sock->lastdata;
      rcvevent = sock->rcvevent;
      sendevent = sock->sendevent;
      errevent = sock->errevent;
    }
    SYS_ARCH_UNPROTECT(lev);
    /* ... then examine it: */
    /* See if netconn of this socket is ready for read */
    if (readset_in && FD_ISSET(i, readset_in) &&
        ((lastdata != NULL) || (rcvevent > 0))) {
      FD_SET(i, &lreadset);
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_selscan: fd=%d ready for reading\n", i));
      nready++;
    }
    /* See if netconn of this socket is ready for write */
    if (writeset_in && FD_ISSET(i, writeset_in) && (sendevent != 0)) {
      FD_SET(i, &lwriteset);
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_selscan: fd=%d ready for writing\n", i));
      nready++;
    }
    /* See if netconn of this socket had an error */
    if (exceptset_in && FD_ISSET(i, exceptset_in) && (errevent != 0)) {
      FD_SET(i, &lexceptset);
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_selscan: fd=%d ready for exception\n", i));
      nready++;
    }
  }
  /* copy local sets to the ones provided as arguments */
  *readset_out = lreadset;
  *writeset_out = lwriteset;
  *exceptset_out = lexceptset;

  LWIP_ASSERT("nready >= 0", nready >= 0);
  return nready;
}

/**
 * Processing exceptset is not yet implemented.
 */
int lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset,
                fd_set *exceptset, struct timeval *timeout) {
  u32_t waitres = 0;
  int nready;
  fd_set lreadset, lwriteset, lexceptset;
  u32_t msectimeout;
  struct lwip_select_cb select_cb;
  err_t err;
  int i;
  SYS_ARCH_DECL_PROTECT(lev);

  LWIP_DEBUGF(
      SOCKETS_DEBUG,
      ("lwip_select(%d, %p, %p, %p, tvsec=%" S32_F " tvusec=%" S32_F ")\n",
       maxfdp1, (void *) readset, (void *) writeset, (void *) exceptset,
       timeout ? (s32_t) timeout->tv_sec : (s32_t) -1,
       timeout ? (s32_t) timeout->tv_usec : (s32_t) -1));

  /* Go through each socket in each list to count number of sockets which
     currently match */
  nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset,
                        &lwriteset, &lexceptset);

  /* If we don't have any current events, then suspend if we are supposed to */
  if (!nready) {
    if (timeout && timeout->tv_sec == 0 && timeout->tv_usec == 0) {
      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: no timeout, returning 0\n"));
      /* This is OK as the local fdsets are empty and nready is zero,
         or we would have returned earlier. */
      goto return_copy_fdsets;
    }

    /* None ready: add our semaphore to list:
       We don't actually need any dynamic memory. Our entry on the
       list is only valid while we are in this function, so it's ok
       to use local variables. */

    select_cb.next = NULL;
    select_cb.prev = NULL;
    select_cb.readset = readset;
    select_cb.writeset = writeset;
    select_cb.exceptset = exceptset;
    select_cb.sem_signalled = 0;
    err = sys_sem_new(&select_cb.sem, 0);
    if (err != ERR_OK) {
      /* failed to create semaphore */
      set_errno(ENOMEM);
      return -1;
    }

    /* Protect the select_cb_list */
    SYS_ARCH_PROTECT(lev);

    /* Put this select_cb on top of list */
    select_cb.next = select_cb_list;
    if (select_cb_list != NULL) {
      select_cb_list->prev = &select_cb;
    }
    select_cb_list = &select_cb;
    /* Increasing this counter tells even_callback that the list has changed. */
    select_cb_ctr++;

    /* Now we can safely unprotect */
    SYS_ARCH_UNPROTECT(lev);

    /* Increase select_waiting for each socket we are interested in */
    for (i = 0; i < maxfdp1; i++) {
      if ((readset && FD_ISSET(i, readset)) ||
          (writeset && FD_ISSET(i, writeset)) ||
          (exceptset && FD_ISSET(i, exceptset))) {
        struct lwip_sock *sock = tryget_socket(i);
        LWIP_ASSERT("sock != NULL", sock != NULL);
        SYS_ARCH_PROTECT(lev);
        sock->select_waiting++;
        LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
        SYS_ARCH_UNPROTECT(lev);
      }
    }

    /* Call lwip_selscan again: there could have been events between
       the last scan (whithout us on the list) and putting us on the list! */
    nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset,
                          &lwriteset, &lexceptset);
    if (!nready) {
      /* Still none ready, just wait to be woken */
      if (timeout == 0) {
        /* Wait forever */
        msectimeout = 0;
      } else {
        msectimeout =
            ((timeout->tv_sec * 1000) + ((timeout->tv_usec + 500) / 1000));
        if (msectimeout == 0) {
          /* Wait 1ms at least (0 means wait forever) */
          msectimeout = 1;
        }
      }

      waitres = sys_arch_sem_wait(&select_cb.sem, msectimeout);
    }
    /* Increase select_waiting for each socket we are interested in */
    for (i = 0; i < maxfdp1; i++) {
      if ((readset && FD_ISSET(i, readset)) ||
          (writeset && FD_ISSET(i, writeset)) ||
          (exceptset && FD_ISSET(i, exceptset))) {
        struct lwip_sock *sock = tryget_socket(i);
        LWIP_ASSERT("sock != NULL", sock != NULL);
        SYS_ARCH_PROTECT(lev);
        sock->select_waiting--;
        LWIP_ASSERT("sock->select_waiting >= 0", sock->select_waiting >= 0);
        SYS_ARCH_UNPROTECT(lev);
      }
    }
    /* Take us off the list */
    SYS_ARCH_PROTECT(lev);
    if (select_cb.next != NULL) {
      select_cb.next->prev = select_cb.prev;
    }
    if (select_cb_list == &select_cb) {
      LWIP_ASSERT("select_cb.prev == NULL", select_cb.prev == NULL);
      select_cb_list = select_cb.next;
    } else {
      LWIP_ASSERT("select_cb.prev != NULL", select_cb.prev != NULL);
      select_cb.prev->next = select_cb.next;
    }
    /* Increasing this counter tells even_callback that the list has changed. */
    select_cb_ctr++;
    SYS_ARCH_UNPROTECT(lev);

    sys_sem_free(&select_cb.sem);
    if (waitres == SYS_ARCH_TIMEOUT) {
      /* Timeout */
      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: timeout expired\n"));
      /* This is OK as the local fdsets are empty and nready is zero,
         or we would have returned earlier. */
      goto return_copy_fdsets;
    }

    /* See what's set */
    nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset,
                          &lwriteset, &lexceptset);
  }

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
return_copy_fdsets:
  set_errno(0);
  if (readset) {
    *readset = lreadset;
  }
  if (writeset) {
    *writeset = lwriteset;
  }
  if (exceptset) {
    *exceptset = lexceptset;
  }

  return nready;
}

/**
 * Callback registered in the netconn layer for each socket-netconn.
 * Processes recvevent (data available) and wakes up tasks waiting for select.
 */
static void event_callback(struct netconn *conn, enum netconn_evt evt,
                           u16_t len) {
  int s;
  struct lwip_sock *sock;
  struct lwip_select_cb *scb;
  int last_select_cb_ctr;
  SYS_ARCH_DECL_PROTECT(lev);

  LWIP_UNUSED_ARG(len);

  /* Get socket */
  if (conn) {
    s = conn->socket;
    if (s < 0) {
      /* Data comes in right away after an accept, even though
       * the server task might not have created a new socket yet.
       * Just count down (or up) if that's the case and we
       * will use the data later. Note that only receive events
       * can happen before the new socket is set up. */
      SYS_ARCH_PROTECT(lev);
      if (conn->socket < 0) {
        if (evt == NETCONN_EVT_RCVPLUS) {
          conn->socket--;
        }
        SYS_ARCH_UNPROTECT(lev);
        return;
      }
      s = conn->socket;
      SYS_ARCH_UNPROTECT(lev);
    }

    sock = get_socket(s);
    if (!sock) {
      return;
    }
  } else {
    return;
  }

  SYS_ARCH_PROTECT(lev);
  /* Set event as required */
  switch (evt) {
    case NETCONN_EVT_RCVPLUS:
      sock->rcvevent++;
      break;
    case NETCONN_EVT_RCVMINUS:
      sock->rcvevent--;
      break;
    case NETCONN_EVT_SENDPLUS:
      sock->sendevent = 1;
      break;
    case NETCONN_EVT_SENDMINUS:
      sock->sendevent = 0;
      break;
    case NETCONN_EVT_ERROR:
      sock->errevent = 1;
      break;
    default:
      LWIP_ASSERT("unknown event", 0);
      break;
  }

  if (sock->select_waiting == 0) {
    /* noone is waiting for this socket, no need to check select_cb_list */
    SYS_ARCH_UNPROTECT(lev);
    return;
  }

/* Now decide if anyone is waiting for this socket */
/* NOTE: This code goes through the select_cb_list list multiple times
   ONLY IF a select was actually waiting. We go through the list the number
   of waiting select calls + 1. This list is expected to be small. */

/* At this point, SYS_ARCH is still protected! */
again:
  for (scb = select_cb_list; scb != NULL; scb = scb->next) {
    if (scb->sem_signalled == 0) {
      /* semaphore not signalled yet */
      int do_signal = 0;
      /* Test this select call for our socket */
      if (sock->rcvevent > 0) {
        if (scb->readset && FD_ISSET(s, scb->readset)) {
          do_signal = 1;
        }
      }
      if (sock->sendevent != 0) {
        if (!do_signal && scb->writeset && FD_ISSET(s, scb->writeset)) {
          do_signal = 1;
        }
      }
      if (sock->errevent != 0) {
        if (!do_signal && scb->exceptset && FD_ISSET(s, scb->exceptset)) {
          do_signal = 1;
        }
      }
      if (do_signal) {
        scb->sem_signalled = 1;
        /* Don't call SYS_ARCH_UNPROTECT() before signaling the semaphore, as
           this might
           lead to the select thread taking itself off the list, invalidagin the
           semaphore. */
        sys_sem_signal(&scb->sem);
      }
    }
    /* unlock interrupts with each step */
    last_select_cb_ctr = select_cb_ctr;
    SYS_ARCH_UNPROTECT(lev);
    /* this makes sure interrupt protection time is short */
    SYS_ARCH_PROTECT(lev);
    if (last_select_cb_ctr != select_cb_ctr) {
      /* someone has changed select_cb_list, restart at the beginning */
      goto again;
    }
  }
  SYS_ARCH_UNPROTECT(lev);
}

/**
 * Unimplemented: Close one end of a full-duplex connection.
 * Currently, the full connection is closed.
 */
int lwip_shutdown(int s, int how) {
  struct lwip_sock *sock;
  err_t err;
  u8_t shut_rx = 0, shut_tx = 0;

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_shutdown(%d, how=%d)\n", s, how));

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  if (sock->conn != NULL) {
    if (netconn_type(sock->conn) != NETCONN_TCP) {
      sock_set_errno(sock, EOPNOTSUPP);
      return EOPNOTSUPP;
    }
  } else {
    sock_set_errno(sock, ENOTCONN);
    return ENOTCONN;
  }

  if (how == SHUT_RD) {
    shut_rx = 1;
  } else if (how == SHUT_WR) {
    shut_tx = 1;
  } else if (how == SHUT_RDWR) {
    shut_rx = 1;
    shut_tx = 1;
  } else {
    sock_set_errno(sock, EINVAL);
    return EINVAL;
  }
  err = netconn_shutdown(sock->conn, shut_rx, shut_tx);

  sock_set_errno(sock, err_to_errno(err));
  return (err == ERR_OK ? 0 : -1);
}

static int lwip_getaddrname(int s, struct sockaddr *name, socklen_t *namelen,
                            u8_t local) {
  struct lwip_sock *sock;
  struct sockaddr_in sin;
  ip_addr_t naddr;

  sock = get_socket(s);
  if (!sock) {
    return -1;
  }

  memset(&sin, 0, sizeof(sin));
  sin.sin_len = sizeof(sin);
  sin.sin_family = AF_INET;

  /* get the IP address and port */
  netconn_getaddr(sock->conn, &naddr, &sin.sin_port, local);

  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getaddrname(%d, addr=", s));
  ip_addr_debug_print(SOCKETS_DEBUG, &naddr);
  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%" U16_F ")\n", sin.sin_port));

  sin.sin_port = htons(sin.sin_port);
  inet_addr_from_ipaddr(&sin.sin_addr, &naddr);

  if (*namelen > sizeof(sin)) {
    *namelen = sizeof(sin);
  }

  MEMCPY(name, &sin, *namelen);
  sock_set_errno(sock, 0);
  return 0;
}

int lwip_getpeername(int s, struct sockaddr *name, socklen_t *namelen) {
  return lwip_getaddrname(s, name, namelen, 0);
}

int lwip_getsockname(int s, struct sockaddr *name, socklen_t *namelen) {
  return lwip_getaddrname(s, name, namelen, 1);
}

int lwip_getsockopt(int s, int level, int optname, void *optval,
                    socklen_t *optlen) {
  err_t err = ERR_OK;
  struct lwip_sock *sock = get_socket(s);
  struct lwip_setgetsockopt_data data;

  if (!sock) {
    return -1;
  }

  if ((NULL == optval) || (NULL == optlen)) {
    sock_set_errno(sock, EFAULT);
    return -1;
  }

  /* Do length and type checks for the various options first, to keep it
   * readable. */
  switch (level) {
    /* Level: SOL_SOCKET */
    case SOL_SOCKET:
      switch (optname) {
        case SO_ACCEPTCONN:
        case SO_BROADCAST:
        /* UNIMPL case SO_DEBUG: */
        /* UNIMPL case SO_DONTROUTE: */
        case SO_ERROR:
        case SO_KEEPALIVE:
/* UNIMPL case SO_CONTIMEO: */
#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
#endif /* LWIP_SO_RCVBUF */
       /* UNIMPL case SO_OOBINLINE: */
       /* UNIMPL case SO_SNDBUF: */
       /* UNIMPL case SO_RCVLOWAT: */
       /* UNIMPL case SO_SNDLOWAT: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
        case SO_TYPE:
          /* UNIMPL case SO_USELOOPBACK: */
          if (*optlen < sizeof(int)) {
            err = EINVAL;
          }
          break;

        case SO_NO_CHECK:
          if (*optlen < sizeof(int)) {
            err = EINVAL;
          }
#if LWIP_UDP
          if ((sock->conn->type != NETCONN_UDP) ||
              ((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0)) {
            /* this flag is only available for UDP, not for UDP lite */
            err = EAFNOSUPPORT;
          }
#endif /* LWIP_UDP */
          break;

        default:
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n", s,
               optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;

    /* Level: IPPROTO_IP */
    case IPPROTO_IP:
      switch (optname) {
        /* UNIMPL case IP_HDRINCL: */
        /* UNIMPL case IP_RCVDSTADDR: */
        /* UNIMPL case IP_RCVIF: */
        case IP_TTL:
        case IP_TOS:
          if (*optlen < sizeof(int)) {
            err = EINVAL;
          }
          break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
          if (*optlen < sizeof(u8_t)) {
            err = EINVAL;
          }
          break;
        case IP_MULTICAST_IF:
          if (*optlen < sizeof(struct in_addr)) {
            err = EINVAL;
          }
          break;
        case IP_MULTICAST_LOOP:
          if (*optlen < sizeof(u8_t)) {
            err = EINVAL;
          }
          if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
            err = EAFNOSUPPORT;
          }
          break;
#endif /* LWIP_IGMP */

        default:
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n", s,
               optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;

#if LWIP_TCP
    /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
      if (*optlen < sizeof(int)) {
        err = EINVAL;
        break;
      }

      /* If this is no TCP socket, ignore any options. */
      if (sock->conn->type != NETCONN_TCP) return 0;

      switch (optname) {
        case TCP_NODELAY:
        case TCP_KEEPALIVE:
#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
        case TCP_KEEPINTVL:
        case TCP_KEEPCNT:
#endif /* LWIP_TCP_KEEPALIVE */
          break;

        default:
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
               s, optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;
#endif /* LWIP_TCP */
#if LWIP_UDP && LWIP_UDPLITE
    /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
      if (*optlen < sizeof(int)) {
        err = EINVAL;
        break;
      }

      /* If this is no UDP lite socket, ignore any options. */
      if (sock->conn->type != NETCONN_UDPLITE) {
        return 0;
      }

      switch (optname) {
        case UDPLITE_SEND_CSCOV:
        case UDPLITE_RECV_CSCOV:
          break;

        default:
          LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, "
                                      "UNIMPL: optname=0x%x, ..)\n",
                                      s, optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;
#endif /* LWIP_UDP && LWIP_UDPLITE*/
       /* UNDEFINED LEVEL */
    default:
      LWIP_DEBUGF(
          SOCKETS_DEBUG,
          ("lwip_getsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n", s,
           level, optname));
      err = ENOPROTOOPT;
  } /* switch */

  if (err != ERR_OK) {
    sock_set_errno(sock, err);
    return -1;
  }

  /* Now do the actual option processing */
  data.sock = sock;
#ifdef LWIP_DEBUG
  data.s = s;
#endif /* LWIP_DEBUG */
  data.level = level;
  data.optname = optname;
  data.optval = optval;
  data.optlen = optlen;
  data.err = err;
  tcpip_callback(lwip_getsockopt_internal, &data);
  sys_arch_sem_wait(&sock->conn->op_completed, 0);
  /* maybe lwip_getsockopt_internal has changed err */
  err = data.err;

  sock_set_errno(sock, err);
  return err ? -1 : 0;
}

static void lwip_getsockopt_internal(void *arg) {
  struct lwip_sock *sock;
#ifdef LWIP_DEBUG
  int s;
#endif /* LWIP_DEBUG */
  int level, optname;
  void *optval;
  struct lwip_setgetsockopt_data *data;

  LWIP_ASSERT("arg != NULL", arg != NULL);

  data = (struct lwip_setgetsockopt_data *) arg;
  sock = data->sock;
#ifdef LWIP_DEBUG
  s = data->s;
#endif /* LWIP_DEBUG */
  level = data->level;
  optname = data->optname;
  optval = data->optval;

  switch (level) {
    /* Level: SOL_SOCKET */
    case SOL_SOCKET:
      switch (optname) {
        /* The option flags */
        case SO_ACCEPTCONN:
        case SO_BROADCAST:
        /* UNIMPL case SO_DEBUG: */
        /* UNIMPL case SO_DONTROUTE: */
        case SO_KEEPALIVE:
/* UNIMPL case SO_OOBINCLUDE: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
          /*case SO_USELOOPBACK: UNIMPL */
          *(int *) optval = ip_get_option(sock->conn->pcb.ip, optname);
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, SOL_SOCKET, optname=0x%x, ..) = %s\n", s,
               optname, (*(int *) optval ? "on" : "off")));
          break;

        case SO_TYPE:
          switch (NETCONNTYPE_GROUP(sock->conn->type)) {
            case NETCONN_RAW:
              *(int *) optval = SOCK_RAW;
              break;
            case NETCONN_TCP:
              *(int *) optval = SOCK_STREAM;
              break;
            case NETCONN_UDP:
              *(int *) optval = SOCK_DGRAM;
              break;
            default: /* unrecognized socket type */
              *(int *) optval = sock->conn->type;
              LWIP_DEBUGF(SOCKETS_DEBUG,
                          ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE): "
                           "unrecognized socket type %d\n",
                           s, *(int *) optval));
          } /* switch (sock->conn->type) */
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE) = %d\n", s,
                       *(int *) optval));
          break;

        case SO_ERROR:
          /* only overwrite ERR_OK or tempoary errors */
          if ((sock->err == 0) || (sock->err == EINPROGRESS)) {
            sock_set_errno(sock, err_to_errno(sock->conn->last_err));
          }
          *(int *) optval = sock->err;
          sock->err = 0;
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, SOL_SOCKET, SO_ERROR) = %d\n", s,
                       *(int *) optval));
          break;

#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
          *(int *) optval = netconn_get_sendtimeout(sock->conn);
          break;
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
          *(int *) optval = netconn_get_recvtimeout(sock->conn);
          break;
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
          *(int *) optval = netconn_get_recvbufsize(sock->conn);
          break;
#endif /* LWIP_SO_RCVBUF */
#if LWIP_UDP
        case SO_NO_CHECK:
          *(int *) optval =
              (udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_NOCHKSUM) ? 1 : 0;
          break;
#endif /* LWIP_UDP*/
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;

    /* Level: IPPROTO_IP */
    case IPPROTO_IP:
      switch (optname) {
        case IP_TTL:
          *(int *) optval = sock->conn->pcb.ip->ttl;
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_IP, IP_TTL) = %d\n", s,
                       *(int *) optval));
          break;
        case IP_TOS:
          *(int *) optval = sock->conn->pcb.ip->tos;
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_IP, IP_TOS) = %d\n", s,
                       *(int *) optval));
          break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
          *(u8_t *) optval = sock->conn->pcb.ip->ttl;
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_TTL) = %d\n", s,
               *(int *) optval));
          break;
        case IP_MULTICAST_IF:
          inet_addr_from_ipaddr((struct in_addr *) optval,
                                &sock->conn->pcb.udp->multicast_ip);
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_IF) = 0x%" X32_F
               "\n",
               s, *(u32_t *) optval));
          break;
        case IP_MULTICAST_LOOP:
          if ((sock->conn->pcb.udp->flags & UDP_FLAGS_MULTICAST_LOOP) != 0) {
            *(u8_t *) optval = 1;
          } else {
            *(u8_t *) optval = 0;
          }
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_LOOP) = %d\n", s,
               *(int *) optval));
          break;
#endif /* LWIP_IGMP */
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;

#if LWIP_TCP
    /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
      switch (optname) {
        case TCP_NODELAY:
          *(int *) optval = tcp_nagle_disabled(sock->conn->pcb.tcp);
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_NODELAY) = %s\n",
                       s, (*(int *) optval) ? "on" : "off"));
          break;
        case TCP_KEEPALIVE:
          *(int *) optval = (int) sock->conn->pcb.tcp->keep_idle;
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPALIVE) = %d\n",
                       s, *(int *) optval));
          break;

#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
          *(int *) optval = (int) (sock->conn->pcb.tcp->keep_idle / 1000);
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPIDLE) = %d\n",
                       s, *(int *) optval));
          break;
        case TCP_KEEPINTVL:
          *(int *) optval = (int) (sock->conn->pcb.tcp->keep_intvl / 1000);
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPINTVL) = %d\n",
                       s, *(int *) optval));
          break;
        case TCP_KEEPCNT:
          *(int *) optval = (int) sock->conn->pcb.tcp->keep_cnt;
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPCNT) = %d\n", s,
                       *(int *) optval));
          break;
#endif /* LWIP_TCP_KEEPALIVE */
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;
#endif /* LWIP_TCP */
#if LWIP_UDP && LWIP_UDPLITE
    /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
      switch (optname) {
        case UDPLITE_SEND_CSCOV:
          *(int *) optval = sock->conn->pcb.udp->chksum_len_tx;
          LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, "
                                      "UDPLITE_SEND_CSCOV) = %d\n",
                                      s, (*(int *) optval)));
          break;
        case UDPLITE_RECV_CSCOV:
          *(int *) optval = sock->conn->pcb.udp->chksum_len_rx;
          LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, "
                                      "UDPLITE_RECV_CSCOV) = %d\n",
                                      s, (*(int *) optval)));
          break;
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;
#endif /* LWIP_UDP */
    default:
      LWIP_ASSERT("unhandled level", 0);
      break;
  } /* switch (level) */
  sys_sem_signal(&sock->conn->op_completed);
}

int lwip_setsockopt(int s, int level, int optname, const void *optval,
                    socklen_t optlen) {
  struct lwip_sock *sock = get_socket(s);
  err_t err = ERR_OK;
  struct lwip_setgetsockopt_data data;

  if (!sock) {
    return -1;
  }

  if (NULL == optval) {
    sock_set_errno(sock, EFAULT);
    return -1;
  }

  /* Do length and type checks for the various options first, to keep it
   * readable. */
  switch (level) {
    /* Level: SOL_SOCKET */
    case SOL_SOCKET:
      switch (optname) {
        case SO_BROADCAST:
        /* UNIMPL case SO_DEBUG: */
        /* UNIMPL case SO_DONTROUTE: */
        case SO_KEEPALIVE:
/* UNIMPL case case SO_CONTIMEO: */
#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
#endif /* LWIP_SO_RCVBUF */
       /* UNIMPL case SO_OOBINLINE: */
       /* UNIMPL case SO_SNDBUF: */
       /* UNIMPL case SO_RCVLOWAT: */
       /* UNIMPL case SO_SNDLOWAT: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
          /* UNIMPL case SO_USELOOPBACK: */
          if (optlen < sizeof(int)) {
            err = EINVAL;
          }
          break;
        case SO_NO_CHECK:
          if (optlen < sizeof(int)) {
            err = EINVAL;
          }
#if LWIP_UDP
          if ((sock->conn->type != NETCONN_UDP) ||
              ((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0)) {
            /* this flag is only available for UDP, not for UDP lite */
            err = EAFNOSUPPORT;
          }
#endif /* LWIP_UDP */
          break;
        default:
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n", s,
               optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;

    /* Level: IPPROTO_IP */
    case IPPROTO_IP:
      switch (optname) {
        /* UNIMPL case IP_HDRINCL: */
        /* UNIMPL case IP_RCVDSTADDR: */
        /* UNIMPL case IP_RCVIF: */
        case IP_TTL:
        case IP_TOS:
          if (optlen < sizeof(int)) {
            err = EINVAL;
          }
          break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
          if (optlen < sizeof(u8_t)) {
            err = EINVAL;
          }
          if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
            err = EAFNOSUPPORT;
          }
          break;
        case IP_MULTICAST_IF:
          if (optlen < sizeof(struct in_addr)) {
            err = EINVAL;
          }
          if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
            err = EAFNOSUPPORT;
          }
          break;
        case IP_MULTICAST_LOOP:
          if (optlen < sizeof(u8_t)) {
            err = EINVAL;
          }
          if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
            err = EAFNOSUPPORT;
          }
          break;
        case IP_ADD_MEMBERSHIP:
        case IP_DROP_MEMBERSHIP:
          if (optlen < sizeof(struct ip_mreq)) {
            err = EINVAL;
          }
          if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
            err = EAFNOSUPPORT;
          }
          break;
#endif /* LWIP_IGMP */
        default:
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n", s,
               optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;

#if LWIP_TCP
    /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
      if (optlen < sizeof(int)) {
        err = EINVAL;
        break;
      }

      /* If this is no TCP socket, ignore any options. */
      if (sock->conn->type != NETCONN_TCP) return 0;

      switch (optname) {
        case TCP_NODELAY:
        case TCP_KEEPALIVE:
#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
        case TCP_KEEPINTVL:
        case TCP_KEEPCNT:
#endif /* LWIP_TCP_KEEPALIVE */
          break;

        default:
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
               s, optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;
#endif /* LWIP_TCP */
#if LWIP_UDP && LWIP_UDPLITE
    /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
      if (optlen < sizeof(int)) {
        err = EINVAL;
        break;
      }

      /* If this is no UDP lite socket, ignore any options. */
      if (sock->conn->type != NETCONN_UDPLITE) return 0;

      switch (optname) {
        case UDPLITE_SEND_CSCOV:
        case UDPLITE_RECV_CSCOV:
          break;

        default:
          LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, "
                                      "UNIMPL: optname=0x%x, ..)\n",
                                      s, optname));
          err = ENOPROTOOPT;
      } /* switch (optname) */
      break;
#endif /* LWIP_UDP && LWIP_UDPLITE */
       /* UNDEFINED LEVEL */
    default:
      LWIP_DEBUGF(
          SOCKETS_DEBUG,
          ("lwip_setsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n", s,
           level, optname));
      err = ENOPROTOOPT;
  } /* switch (level) */

  if (err != ERR_OK) {
    sock_set_errno(sock, err);
    return -1;
  }

  /* Now do the actual option processing */
  data.sock = sock;
#ifdef LWIP_DEBUG
  data.s = s;
#endif /* LWIP_DEBUG */
  data.level = level;
  data.optname = optname;
  data.optval = (void *) optval;
  data.optlen = &optlen;
  data.err = err;
  tcpip_callback(lwip_setsockopt_internal, &data);
  sys_arch_sem_wait(&sock->conn->op_completed, 0);
  /* maybe lwip_setsockopt_internal has changed err */
  err = data.err;

  sock_set_errno(sock, err);
  return err ? -1 : 0;
}

static void lwip_setsockopt_internal(void *arg) {
  struct lwip_sock *sock;
#ifdef LWIP_DEBUG
  int s;
#endif /* LWIP_DEBUG */
  int level, optname;
  const void *optval;
  struct lwip_setgetsockopt_data *data;

  LWIP_ASSERT("arg != NULL", arg != NULL);

  data = (struct lwip_setgetsockopt_data *) arg;
  sock = data->sock;
#ifdef LWIP_DEBUG
  s = data->s;
#endif /* LWIP_DEBUG */
  level = data->level;
  optname = data->optname;
  optval = data->optval;

  switch (level) {
    /* Level: SOL_SOCKET */
    case SOL_SOCKET:
      switch (optname) {
        /* The option flags */
        case SO_BROADCAST:
        /* UNIMPL case SO_DEBUG: */
        /* UNIMPL case SO_DONTROUTE: */
        case SO_KEEPALIVE:
/* UNIMPL case SO_OOBINCLUDE: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
          /* UNIMPL case SO_USELOOPBACK: */
          if (*(int *) optval) {
            ip_set_option(sock->conn->pcb.ip, optname);
          } else {
            ip_reset_option(sock->conn->pcb.ip, optname);
          }
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, SOL_SOCKET, optname=0x%x, ..) -> %s\n", s,
               optname, (*(int *) optval ? "on" : "off")));
          break;
#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
          netconn_set_sendtimeout(sock->conn, (s32_t) * (int *) optval);
          break;
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
          netconn_set_recvtimeout(sock->conn, *(int *) optval);
          break;
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
          netconn_set_recvbufsize(sock->conn, *(int *) optval);
          break;
#endif /* LWIP_SO_RCVBUF */
#if LWIP_UDP
        case SO_NO_CHECK:
          if (*(int *) optval) {
            udp_setflags(sock->conn->pcb.udp,
                         udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_NOCHKSUM);
          } else {
            udp_setflags(sock->conn->pcb.udp,
                         udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_NOCHKSUM);
          }
          break;
#endif /* LWIP_UDP */
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;

    /* Level: IPPROTO_IP */
    case IPPROTO_IP:
      switch (optname) {
        case IP_TTL:
          sock->conn->pcb.ip->ttl = (u8_t)(*(int *) optval);
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_setsockopt(%d, IPPROTO_IP, IP_TTL, ..) -> %d\n", s,
                       sock->conn->pcb.ip->ttl));
          break;
        case IP_TOS:
          sock->conn->pcb.ip->tos = (u8_t)(*(int *) optval);
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_setsockopt(%d, IPPROTO_IP, IP_TOS, ..)-> %d\n", s,
                       sock->conn->pcb.ip->tos));
          break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
          sock->conn->pcb.udp->ttl = (u8_t)(*(u8_t *) optval);
          break;
        case IP_MULTICAST_IF:
          inet_addr_to_ipaddr(&sock->conn->pcb.udp->multicast_ip,
                              (struct in_addr *) optval);
          break;
        case IP_MULTICAST_LOOP:
          if (*(u8_t *) optval) {
            udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) |
                                                  UDP_FLAGS_MULTICAST_LOOP);
          } else {
            udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) &
                                                  ~UDP_FLAGS_MULTICAST_LOOP);
          }
          break;
        case IP_ADD_MEMBERSHIP:
        case IP_DROP_MEMBERSHIP: {
          /* If this is a TCP or a RAW socket, ignore these options. */
          struct ip_mreq *imr = (struct ip_mreq *) optval;
          ip_addr_t if_addr;
          ip_addr_t multi_addr;
          inet_addr_to_ipaddr(&if_addr, &imr->imr_interface);
          inet_addr_to_ipaddr(&multi_addr, &imr->imr_multiaddr);
          if (optname == IP_ADD_MEMBERSHIP) {
            data->err = igmp_joingroup(&if_addr, &multi_addr);
          } else {
            data->err = igmp_leavegroup(&if_addr, &multi_addr);
          }
          if (data->err != ERR_OK) {
            data->err = EADDRNOTAVAIL;
          }
        } break;
#endif /* LWIP_IGMP */
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;

#if LWIP_TCP
    /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
      switch (optname) {
        case TCP_NODELAY:
          if (*(int *) optval) {
            tcp_nagle_disable(sock->conn->pcb.tcp);
          } else {
            tcp_nagle_enable(sock->conn->pcb.tcp);
          }
          LWIP_DEBUGF(SOCKETS_DEBUG,
                      ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_NODELAY) -> %s\n",
                       s, (*(int *) optval) ? "on" : "off"));
          break;
        case TCP_KEEPALIVE:
          sock->conn->pcb.tcp->keep_idle = (u32_t)(*(int *) optval);
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPALIVE) -> %" U32_F
               "\n",
               s, sock->conn->pcb.tcp->keep_idle));
          break;

#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
          sock->conn->pcb.tcp->keep_idle = 1000 * (u32_t)(*(int *) optval);
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPIDLE) -> %" U32_F "\n",
               s, sock->conn->pcb.tcp->keep_idle));
          break;
        case TCP_KEEPINTVL:
          sock->conn->pcb.tcp->keep_intvl = 1000 * (u32_t)(*(int *) optval);
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPINTVL) -> %" U32_F
               "\n",
               s, sock->conn->pcb.tcp->keep_intvl));
          break;
        case TCP_KEEPCNT:
          sock->conn->pcb.tcp->keep_cnt = (u32_t)(*(int *) optval);
          LWIP_DEBUGF(
              SOCKETS_DEBUG,
              ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPCNT) -> %" U32_F "\n",
               s, sock->conn->pcb.tcp->keep_cnt));
          break;
#endif /* LWIP_TCP_KEEPALIVE */
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;
#endif /* LWIP_TCP*/
#if LWIP_UDP && LWIP_UDPLITE
    /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
      switch (optname) {
        case UDPLITE_SEND_CSCOV:
          if ((*(int *) optval != 0) &&
              ((*(int *) optval < 8) || (*(int *) optval > 0xffff))) {
            /* don't allow illegal values! */
            sock->conn->pcb.udp->chksum_len_tx = 8;
          } else {
            sock->conn->pcb.udp->chksum_len_tx = (u16_t) * (int *) optval;
          }
          LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, "
                                      "UDPLITE_SEND_CSCOV) -> %d\n",
                                      s, (*(int *) optval)));
          break;
        case UDPLITE_RECV_CSCOV:
          if ((*(int *) optval != 0) &&
              ((*(int *) optval < 8) || (*(int *) optval > 0xffff))) {
            /* don't allow illegal values! */
            sock->conn->pcb.udp->chksum_len_rx = 8;
          } else {
            sock->conn->pcb.udp->chksum_len_rx = (u16_t) * (int *) optval;
          }
          LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, "
                                      "UDPLITE_RECV_CSCOV) -> %d\n",
                                      s, (*(int *) optval)));
          break;
        default:
          LWIP_ASSERT("unhandled optname", 0);
          break;
      } /* switch (optname) */
      break;
#endif /* LWIP_UDP */
    default:
      LWIP_ASSERT("unhandled level", 0);
      break;
  } /* switch (level) */
  sys_sem_signal(&sock->conn->op_completed);
}

int lwip_ioctl(int s, long cmd, void *argp) {
  struct lwip_sock *sock = get_socket(s);
  u8_t val;
#if LWIP_SO_RCVBUF
  u16_t buflen = 0;
  s16_t recv_avail;
#endif /* LWIP_SO_RCVBUF */

  if (!sock) {
    return -1;
  }

  switch (cmd) {
#if LWIP_SO_RCVBUF
    case FIONREAD:
      if (!argp) {
        sock_set_errno(sock, EINVAL);
        return -1;
      }

      SYS_ARCH_GET(sock->conn->recv_avail, recv_avail);
      if (recv_avail < 0) {
        recv_avail = 0;
      }
      *((u16_t *) argp) = (u16_t) recv_avail;

      /* Check if there is data left from the last recv operation. /maq 041215
       */
      if (sock->lastdata) {
        struct pbuf *p = (struct pbuf *) sock->lastdata;
        if (netconn_type(sock->conn) != NETCONN_TCP) {
          p = ((struct netbuf *) p)->p;
        }
        buflen = p->tot_len;
        buflen -= sock->lastoffset;

        *((u16_t *) argp) += buflen;
      }

      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, FIONREAD, %p) = %" U16_F "\n",
                                  s, argp, *((u16_t *) argp)));
      sock_set_errno(sock, 0);
      return 0;
#endif /* LWIP_SO_RCVBUF */

    case FIONBIO:
      val = 0;
      if (argp && *(u32_t *) argp) {
        val = 1;
      }
      netconn_set_nonblocking(sock->conn, val);
      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, FIONBIO, %d)\n", s, val));
      sock_set_errno(sock, 0);
      return 0;

    default:
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_ioctl(%d, UNIMPL: 0x%lx, %p)\n", s, cmd, argp));
      sock_set_errno(sock, ENOSYS); /* not yet implemented */
      return -1;
  } /* switch (cmd) */
}

/** A minimal implementation of fcntl.
 * Currently only the commands F_GETFL and F_SETFL are implemented.
 * Only the flag O_NONBLOCK is implemented.
 */
int lwip_fcntl(int s, int cmd, int val) {
  struct lwip_sock *sock = get_socket(s);
  int ret = -1;

  if (!sock || !sock->conn) {
    return -1;
  }

  switch (cmd) {
    case F_GETFL:
      ret = netconn_is_nonblocking(sock->conn) ? O_NONBLOCK : 0;
      break;
    case F_SETFL:
      if ((val & ~O_NONBLOCK) == 0) {
        /* only O_NONBLOCK, all other bits are zero */
        netconn_set_nonblocking(sock->conn, val & O_NONBLOCK);
        ret = 0;
      }
      break;
    default:
      LWIP_DEBUGF(SOCKETS_DEBUG,
                  ("lwip_fcntl(%d, UNIMPL: %d, %d)\n", s, cmd, val));
      break;
  }
  return ret;
}

#endif /* LWIP_SOCKET */
